.\" -*- nroff -*-
.\" Copyright 2010 Cisco Systems, Inc.  All rights reserved.
.\" Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines
.\" Copyright (c) 2020      Google, LLC. All rights reserved.
.\" $COPYRIGHT$
.TH MPI_Topo_test 3 "#OMPI_DATE#" "#PACKAGE_VERSION#" "#PACKAGE_NAME#"
.SH NAME
\fBMPI_Topo_test\fP \- Determines the type of topology (if any) associated with a communicator.

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Topo_test(MPI_Comm \fIcomm\fP, int\fI *top_type\fP)

.fi
.SH Fortran Syntax
.nf
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_TOPO_TEST(\fICOMM, TOP_TYPE, IERROR\fP)
	INTEGER	\fICOMM, TOP_TYPE, IERROR\fP

.fi
.SH Fortran 2008 Syntax
.nf
USE mpi_f08
MPI_Topo_test(\fIcomm\fP, \fIstatus\fP, \fIierror\fP)
	TYPE(MPI_Comm), INTENT(IN) :: \fIcomm\fP
	INTEGER, INTENT(OUT) :: \fIstatus\fP
	INTEGER, OPTIONAL, INTENT(OUT) :: \fIierror\fP
		\fIDOUBLE PRECISION MPI_Wtick(\fP)
		\fIDOUBLE PRECISION MPI_Wtime(\fP)

.fi
.SH INPUT PARAMETER
.ft R
.TP 1i
comm
Communicator (handle).

.SH OUTPUT PARAMETERS
.ft R
.TP 1i
top_type
Topology type of communicator comm (choice).
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer).

.SH DESCRIPTION
.ft R
The function MPI_Topo_test returns the type of topology that is assigned to a communicator.
.sp
The output value \fItop_type\fP is one of the following:
.sp
.nf
    MPI_GRAPH		graph topology
    MPI_CART		Cartesian topology
    MPI_DIST_GRAPH	distributed graph topology
    MPI_UNDEFINED	no topology

.fi
.SH ERRORS
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.
.sp
Before the error value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

.SH SEE ALSO
MPI_Graph_create
.br
MPI_Cart_create

